Management of hair loss

Minoxidil, applied topically, is widely used for the treatment of hair loss. It may be effective in helping promote hair growth in both men and women with androgenic alopecia.[6][7] About 40% of men experience hair regrowth after 3–6 months.[8] It is the only topical product that is FDA approved in America for androgenic hair loss.[6] However, increased hair loss has been reported.[9][10]

Finasteride is used to treat male pattern hair loss.[11] Treatment provides about 30% improvement in hair loss after six months of treatment, and effectiveness only persists as long as the drug is taken.[12] There is no good evidence for its use in women.[1] It may cause gynecomastia, erectile dysfunction and depression.[13]

Dutasteride is used off label for male pattern hair loss.[14]

There is tentative support for spironolactone in women.[1] Due to its feminising side effects and risk of infertility it is not often used by men.[15][16] It can also cause low blood pressure, high blood potassium, and abnormal heart rhythms. Also, women who are pregnant or trying to become pregnant generally cannot use the medication as it is a teratogen, and can cause ambiguous genitalia in newborn children.[17]

There is tentative evidence for flutamide in women; however, it is associated with relatively high rates of liver problems.[1] Like spironolactone, it is typically only used by women.[18]

Ketoconazole may help in women.[1]

A man before and after a hair transplant.

Hair transplantation is a surgical technique that moves individual hair follicles from a part of the body called the donor site to bald or balding part of the body known as the recipient site. It is primarily used to treat male pattern baldness. In this condition, grafts containing hair follicles that are genetically resistant to balding are transplanted to bald scalp. It is also used to restore eyelashes, eyebrows, beard hair, chest hair, and pubic hair and to fill in scars caused by accidents or surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.

Since hair naturally grows in follicles in groups of 1 to 4 hairs, transplantation takes advantage of these naturally occurring follicular units. This achieves a more natural appearance by matching hair for hair through Follicular unit transplantation (FUT).

Donor hair can be harvested in two different ways. Small grafts of naturally-occurring units of one to four hairs, called follicular units, can be moved to balding areas of the hair restoration. These follicular units are surgically implanted in the scalp in very close proximity to one another and in large numbers. The grafts are obtained in one or both of the two primary methods of surgical extraction, follicular unit transplantation, colloquially referred to as "strip harvesting", or Follicular Unit Extraction (FUE), in which follicles are transplanted individually.

In FUT, a strip of skin containing many follicular units is extracted from the patient and dissected under a stereoscopic microscope. The site of the strip removal is stitched closed. Once divided into follicular unit grafts, each unit is individually inserted into small recipient sites made by an incision in the bald scalp. In the newer technique, roots are extracted from the donor area and divided into strips for transplantation. The strip, two to three millimeters thick, is isolated and transplanted to the bald scalp.[19] After surgery, a bandage is worn for two days to protect the stitched strip during healing. A small strip scar remains after healing, which can be covered by scalp hair growing over the scar.[20]

Scalp reduction is a surgical procedure in which the hairless region of the scalp of a bald man is reduced. This procedure can reduce the area of the scalp without hair.[21][22]

2008 and 2012 reviews found little evidence to support the use of special lights or lasers to treat hair loss.[1][31][32][33] Both laser and lights appear to be safe.[31]

A 2014 and 2016 review found tentative evidence of benefit for lasers.[34][35] While another 2014 review concluded that the results are mixed, have a high risk of bias, and that its effectiveness is unclear.[36]

Dietary supplements are not typically recommended.[31] There is only one small trial of saw palmetto which shows tentative benefit in those with mild to moderate androgenetic alopecia.[31] There is no evidence for biotin.[31] Evidence for most other products is also insufficient. There was no good evidence for gingko, aloe vera, ginseng, bergamot, or hibiscus as of 2011.[37] While lacking both evidence and expert recommendation, there is a large market for hair growth supplements, especially for products that contain biotin.

Latanoprost and bimatoprost are specific PGF2a analogues applied topically, and have been found to lengthen eyelashes,[43][44] darken hair pigmentation[45] and elongate hair.[4] Bimatoprost is available as treatment for eyelash growth.[46] Latanoprost has shown ability to promote scalp hair density and pigmentation,[47] and is theorized to function at the dermal papilla.[48] A study found latanoprost ineffective on eyelashes in a patient with alopecia areata.[49] It has also been found ineffective in treatment of eyebrow hair loss.[50]

Estrogens are indirect anti-androgens and can be used to treat androgenetic hair loss in women with oral contraceptives. Systemic estrogen increases SHBG, which binds androgens, including testosterone and DHT, in turn reducing their bioavailability. Topical formulations are available in Europe.[37] Hair follicles have estrogen receptors and it is theorized that topical compounds act on them directly to promote hair growth and antagonize androgen action. Large clinical studies showing effectiveness are absent. Topical treatment is also usually unavailable in North America.[4]

There is tentative evidence for cyproterone acetate in women.[1]

In December 2012, topical application of IGF-1 in a liposomal vehicle led to thicker and more rapid hair growth in transgenic mice with androgenic alopecia. The study did not show measurable systemic levels or hematopoietic side effects, suggesting potential for use in humans.[51] Low energy radiofrequency irradiation induces IGF-1 in cultured human dermal papilla cells.[52] Adenosine stimulates dermal papillae in vitro to induce IGF-1, along with fibroblast growth factors FGF7, FGF-2 and VEGF. β-catenin transcription increased, which promotes dermal papillae as well.[52] Dietary isoflavones increase IGF production in scalp dermal papillae in transgenic mice.[53] Topical capsaicin also stimulates IGF at hair follicles via release of vanilloid receptor-1, which in turn leads to more CGRP.[54] Ascorbic acid has led to increased IGF expression in vitro.[55]

Reviews in 2013 and 2017 on the use of platelet-rich plasma (PRP) to regrow hair found insufficient evidence to draw clear conclusions.[56][57]

Although follicles were previously thought gone in areas of complete baldness, they are more likely dormant, as recent studies have shown the scalp contains the stem cells from which the follicles arose.[58] Research on these follicular stem cells may lead to successes in treating baldness through hair multiplication (HM), also known as hair cloning.

Per a May 2015 review, no successful strategy to generate human hair follicles, for hair regrowth, from adult stem cells has yet been reported.[59] However, in April 2016, scientists from Japan published results of their work in which they created human skin from induced pluripotent stem cells; implanted into laboratory mice, the cells generated skin with hair and glands.[60]

From 2005 to 2007 Curis and Procter & Gamble collaborated on developing a topical hedgehog agonist for hair loss; the agent did not meet safety standards, and the program was terminated.[61][62] In 2008 researchers at the University of Bonn announced they have found the genetic basis of two distinct forms of inherited hair loss. They found the gene P2RY5 causes a rare, inherited form of hair loss called hypotrichosis simplex. It is the first receptor in humans known to play a role in hair growth.[63][64][65] Researchers found that disruption of the gene SOX21 in mice caused cyclical hair loss. Research has suggested SOX21 as a master regulator of hair shaft cuticle differentiation, with its disruption causing cyclical alopecia in mice models.[66] Deletion of SOX21 dramatically affects hair lipids.[67]